1. Field of the Invention
The present invention relates to an array substrate for a liquid crystal display (LCD) device and more particularly to an array substrate for an LCD device being capable of preventing damages from a static electricity.
2. Discussion of the Related Art
A related art liquid crystal display (LCD) device uses optical anisotropy and polarization properties of liquid crystal molecules. The liquid crystal molecules have a definite alignment direction as a result of their thin and long shapes. The alignment direction of the liquid crystal molecules can be controlled by applying an electric field across the liquid crystal molecules. In other words, as the intensity or direction of the electric field is changed, the alignment of the liquid crystal molecules also changes. Since incident light is refracted based on the orientation of the liquid crystal molecules due to the optical anisotropy of the liquid crystal molecules, images can be displayed by controlling light transmissivity.
Since the LCD device including a thin film transistor (TFT) as a switching element, referred to as an active matrix LCD (AM-LCD) device, has excellent characteristics of high resolution and displaying moving images, the AM-LCD device has been widely used.
FIG. 1 is a schematic plan view showing the related art LCD device. In FIG. 1, the LCD device 1 includes a color filter substrate 50, an array substrate 10 and a liquid crystal layer (not shown) therebetween. A display region AA for displaying images and a non-display region (NAA) at a periphery of the display region AA are defined on each of the color filter substrate 50 and the array substrate 10. The color filter substrate 50, the array substrate 10 and the liquid crystal layer (not shown) constitute a liquid crystal panel.
Although not shown, a black matrix for blocking light from a backlight unit (not shown) and corresponding to the non-display region NAA, a color filter layer including sub-color filters of red, green and blue colors and corresponding to the display region AA, and a common electrode on an entire lower surface of the color filter layer are formed on a lower surface of the color filter substrate 50.
A plurality of gate lines 20, a plurality of data lines 30, a plurality of thin film transistors (TFTs) T and a plurality of pixel electrodes 70 are formed in the display region AA of the array substrate 10. The gate lines 20 receive a scanning signal. The data lines 30 receive a data signal and cross the gate lines 20 to define a plurality of pixel regions P. Each of the TFTs T is disposed at each crossing portion of the gate and data lines 20 and 30. Each of the pixel electrodes 70 is connected to each TFT and disposed in each pixel region P.
In addition, a plurality of gate extending lines 22 and a plurality of data extending lines 32 are formed in the non-display region NAA of the array substrate 10. Each of the gate extending lines 22 is connected to each gate line 20 and applies the scanning signal from a drive integrate circuit (IC) 35 into the each gate line 20. Each of the data extending lines 32 is connected to each data line 30 and applies the data signal from the drive IC 35 into the each data line 30.
A common voltage line 50 is formed on edges of the non-display region NAA. The common voltage line 50 applies a common signal from an external common voltage generating unit (not shown) through a flexible printed circuit (FPC) 90 into the common electrode (not shown) on an entire surface of the color filter substrate 50 through a plurality of conductive units 86 at four corners of the liquid crystal panel. First and second test pads 60 and 62 for testing properties of the scanning and data signals, for example, a waveform or/and a magnitude of the signals, is formed at both sides of the drive IC 35, respectively. A pad unit 75 connected to the FPC 90 is positioned at a lower side of drive IC 35. The pad unit 75 connected to the FPC 90 receives a driving voltage from an external system (not shown) through a FPC connector 92. The conductive units 186 may include a silver dot.
An arrangement of liquid crystal molecules in the liquid crystal layer (not shown) is changed by a potential difference between the common voltage applied to the common electrode (not shown) and the data signal applied to the pixel electrode 70 through the drive IC 35 and the TFT T in a period, images are displayed by controlling light transmissivity depending on the arrangement of the liquid crystal molecules in the above-mentioned LCD device 1.
A static electricity is not induced on the array substrate 10 of a silica-based glass. However, in a process of forming electrodes and lines on the array substrate 10, a static electricity may be induced at the drive IC 35 and the first and second test pads 60 and 62 because of particles in a processing chamber or a pulse-type current.
The static electricity induced at the drive IC 35 and the first and second test pads 60 and 62 flows into the gate and data lines 20 and 30 such that a desired operation of the TFT can not be obtained. Accordingly, a production yield is reduced.